The present invention relates to sieve trays for a sieve devices. These sieve trays usually have at least one sieve netting consisting of a wire netting, and each wire netting contains warp and weft wires mutually connected by a weave.
The above-referenced sieve trays are known in many constructions. Each sieve tray has an upper sieve netting, relative to an installed position, and a supporting netting, situated below, which has a larger mesh size. The mesh sizes of the sieve nettings depend on the sizes of the particles to be sieved. The sieve trays normally have a round or square design. Frequently, the sieve trays are also provided with tensioning edges in order to tension the sieve netting either transversely to the flow direction of the material or in the longitudinal direction of the material. The so-called tensioning edges are also known in various constructions. In order to separate particles from a material such as a liquid, an emulsion, or the like, two different methods are known. There is sieving by a sieve device or filtering by a filter device. For the sieving, the above-mentioned sieve tray can be used which, by a vibration generator, is caused to carry out a swinging motion.
In the case of the above-mentioned sieve trays, the wire netting may consist exclusively of warp wires and weft wires which extend at a right angle thereto. As a result, square meshes or openings are created in the projection. Such sieve trays have been very successful but are not completely satisfactory for certain applications, such as the sieving of particles of a certain size from an emulsion.
An aspect of the present invention is having a sieve tray configured such that particles of a certain size can be sieved out of a material, such as a liquid, an emulsion or the like.
This aspect, at least, is addressed by having sieve netting that is provided with mutually spaced alternating crossings situated diagonally to warp and weft wires.
The size of meshes or openings are no longer necessarily determined by spaces between the warp and weft wires but gores are formed which are no longer square. The size of the gores is a function of the positions of the alternating crossings with respect to the warp and weft wires. The warp and weft wires may be in contact with one another in a twill-lace weave. The alternating crossings additionally contribute to stabilization of the sieve netting because they also include wires.
In a preferred embodiment, the alternating crossings extend in a zigzag shape from one edge to the opposite edge. The alternating crossings extend from the edges which extend parallel and at a distance from the warp wires. The zigzag-shaped course of the alternating crossings additionally increases the stability, so that the service life of a sieve tray can be extended. So that a uniform mesh size is achieved over the entire sieve surface, each straight-lined section of the alternating crossings extends over a constant number of warp wires. In a preferred embodiment, in which the warp wires and the weft wires are situated at equal mutual distances and therefore form square meshes, the straight-lined sections of the alternating crossings also extend over the same number of weft wires as warp wires. The individual straight-lined sections of the alternating crossings will then be situated at an angle of 45° with respect to the warp and weft wires. In a preferred embodiment, the straight-lined sections of the alternating weft wires maximally extend, for example, over 20 warp wires.
In a preferred embodiment, the weaves of the warp and weft wires are zz-weaves. As a result, favorable conditions are obtained for the weaves of the alternating crossings. In a preferred embodiment, a side change of the warp wires takes place when they have skipped a certain number of weft wires, and this number corresponds to the warp wires skipped by the weft wires. In a preferred embodiment, the number of skipped warp wires amounts to two. The respective sections of the warp and the weft threads situated on one side are offset from one warp wire to the next warp wire by one weft wire. The sections of the weft wires situated on one side are also offset with respect to one another by one warp wire from one weft wire to the next.
Depending on the construction, the diameters of the warp wires 14 and the weft wires 15 may be the same as or coincide or approximately coincide, but may also be different. The diameters of the alternating crossings may coincide with or be the same as the diameters of the warp wires and, if the diameters of the weft wires deviate therefrom, may also coincide with or be the same as the diameters of the weft wires or approximately coincide. However, constructions are also conceivable in which the diameters of the alternating crossings deviate from the diameters of the warp wires as well as of the weft wires. Depending on an application's purpose, a supporting netting also can be functionally assigned to the sieve netting. The mesh width of this supporting netting is normally larger than that of the sieve netting.
The sieve trays are considered to be fine-meshed. So that a uniform tension is ensured along the entire width or the entire length, the sieve tray is equipped with one tensioning edge respectively on two mutually opposite sides, which tensioning edge is formed by shaping. As an alternative, the sieve netting may also be clamped onto a frame. For compensating tension differences in the sieve netting, a flexible element, preferably a plastic element, may be worked into at least one tensioning edge.
The invention will be better understood and appreciated from the following detailed descriptions and with reference to the accompanying drawings.